<template>
  <div class="goods-image">
    <!-- 添加预览大图 -->
    <div v-show='isShow' class="large" :style='[{backgroundImage: `url(${images[currIndex]})`}, bgPosition]'></div>
    <!-- 左侧的大图 -->
    <div class="middle" ref='target'>
      <img :src="images[currIndex]" alt="">
      <!-- 遮罩层 -->
      <div v-show='isShow' class="layer" :style='position'></div>
    </div>
    <!-- 右侧的小图片 -->
    <ul class="small">
      <li v-for="(img,i) in images" :key="img" :class="{active:i===currIndex}">
        <img @mouseenter="currIndex=i" :src="img" alt="">
      </li>
    </ul>
  </div>
</template>
<script>
import { ref, watch, reactive } from 'vue'
import { useMouseInElement } from '@vueuse/core'

const usePreviewImage = () => {
  // 被监听的区域
  const target = ref(null)
  // 控制遮罩层和预览图的显示和隐藏
  const isShow = ref(false)
  // 遮罩层位置坐标
  const position = reactive({
    left: 0,
    top: 0
  })
  // 右侧预览大图的坐标
  const bgPosition = reactive({
    backgroundPositionX: 0,
    backgroundPositionY: 0
  })
  const { elementX, elementY, isOutside } = useMouseInElement(target)
  // 基于侦听器侦听值的变化
  watch([elementX, elementY, isOutside], () => {
    // console.log(elementX.value, elementY.value, isOutside.value)
    // 通过标志位控制显示和隐藏
    isShow.value = !isOutside.value
    if (isOutside.value) return
    // X方向坐标范围控制
    if (elementX.value < 100) {
      // 左侧
      position.left = 0
    } else if (elementX.value > 300) {
      // 右侧
      position.left = 200
    } else {
      // 中间
      position.left = elementX.value - 100
    }
    // Y方向坐标范围控制
    if (elementY.value < 100) {
      // 左侧
      position.top = 0
    } else if (elementY.value > 300) {
      // 右侧
      position.top = 200
    } else {
      // 中间
      position.top = elementY.value - 100
    }
    // 计算预览大图的移动的距离
    bgPosition.backgroundPositionX = -position.left * 2 + 'px'
    bgPosition.backgroundPositionY = -position.top * 2 + 'px'
    // 计算遮罩层的位置
    position.left = position.left + 'px'
    position.top = position.top + 'px'
  })

  return { position, bgPosition, isShow, target }
}

export default {
  name: 'GoodsImage',
  props: {
    images: {
      type: Array,
      default: () => []
    }
  },
  setup (props) {
    // 记录当前选中的图片的索引
    const currIndex = ref(0)
    const { position, bgPosition, isShow, target } = usePreviewImage()
    return { currIndex, position, bgPosition, target, isShow }
  }
}
</script>
<style scoped lang="less">
.goods-image {
  width: 480px;
  height: 400px;
  position: relative;
  display: flex;
  z-index: 500;
  .large {
    position: absolute;
    top: 0;
    left: 412px;
    width: 400px;
    height: 400px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    background-repeat: no-repeat;
    background-size: 800px 800px;
    background-color: #f8f8f8;
  }
  .middle {
    width: 400px;
    height: 400px;
    background: #f5f5f5;
    position: relative;
    cursor: move;
    .layer {
      width: 200px;
      height: 200px;
      background: rgba(0, 0, 0, 0.2);
      left: 0;
      top: 0;
      position: absolute;
    }
  }
  .small {
    width: 80px;
    li {
      width: 68px;
      height: 68px;
      margin-left: 12px;
      margin-bottom: 15px;
      cursor: pointer;
      &:hover,
      &.active {
        border: 2px solid @xtxColor;
      }
    }
  }
}
</style>
